New Equivalent Circuit Model for a Broadband Optimization of Dipole Arrays

Equivalent circuits are frequently used as optimization tools for the design of dipole arrays. Previous approaches exist, but are valid only on tight bandwidths or do not model the array input impedance in both broadside and scan configurations. In this letter, we propose a new equivalent circuit that provides a large representation of dipole arrays from DC to the first free-space grating lobe frequency. This model is efficient for arrays of connected as well as tightly coupled dipoles operating in the E- and H-planes, and it can take into account a ground plane and dielectric layers. Based on the proposed equivalent circuit model, an optimization process can be implemented in order to find the dielectric arrangement and the ground plane distance that offer the best performances in both bandwidth and scanning capabilities. The optimization example given in this letter shows an active voltage standing wave ratio (VSWR) less than 2 over a 4.5:1 bandwidth at broadside and at least a 3.4:1 bandwidth up to 40 ^° in the E-, H-, and D-planes.